Note: Descriptions are shown in the official language in which they were submitted.
CA 02784184 2015-11-25
DOWN-HOLE SAND AND SOLIDS SEPARATOR UTILIZED IN PRODUCING
HYDROCARBONS
TECHNICAL FIELD
[0001] The present disclosure is directed to petroleum producing and
injection
wells and more particularly to the removal of particulates, such as sand, from
the production
stream.
BACKGROUND OF THE INVENTION
[0002] Petroleum wells can be naturally flowing, injecting or can be
produced
by any means of artificial lift. Particulates within the production stream,
which can include
both liquid and gaseous products, can be both naturally occurring and manmade.
Such
particulates can include sand, silt, and other solids and are a natural
byproduct of the
producing wells. As hydrocarbons and water flow through the formation, these
particulates
are carried in the flow stream and can be carried into the production tubing
which can cause
problems with the tubing or artificial lifting mechanism, such as a rod pump.
[0003] With an increase in fracturing of wells designed to increase
the well's
production, there has been an increase in fracture sand, the most common
manmade
particulate found at the wellhead. Fracture sand is commonly introduced into
the reservoir in
an effort to create conductive channels from the reservoir rock into the
wellbore, thereby
allowing the hydrocarbons a much easier flow path into the tubing and up to
the surface of
the well.
[0004] Natural or manmade particulates can cause a multitude of
producing
problems for oil and gas operators. For example, in flowing wells abrasive
particulates can
"wash through" metals in piping creating leaks and potentially hazardous
conditions.
Particulates can also fill-up and stop-up surface flow lines, vessels, and
tanks. In reservoirs
whereby some type of artificial lift is required such as rod pumping, electric
submersible
pumps, progressive cavity, and other methods, production of particulates can
reduce of the
life of the down-hole assembly and increase maintenance cost.
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BRIEF SUMMARY OF THE INVENTION
[0004a] Certain exemplary embodiments can provide a particulate
separator for
use with a petroleum production well producing a fluid mixture including
particulate matter,
the separator comprising: a velocity stage having an outer casing and an inner
tube, the outer
casing including intake slots positioned above a pump intake at a bottom end
of the inner
tube, the intake slots allowing the fluid mixture to enter the space between
the outer casing
and inner tube and to flow downward toward the pump intake, wherein the fluid
mixture
reaches a downward velocity sufficient to allow the particulate matter in the
fluid mixture to
continue downward as the fluid is drawn into the inner tube through the pump
intake; and a
filter stage wherein the fluid mixture is drawn through a filter medium to
filter the particulate
matter from the fluid mixture.
[0004b] Certain exemplary embodiments can provide a method for
separating
particulate matter from a fluid mixture for use with a petroleum production
well producing,
the method comprising: drawing the fluid mixture into a velocity stage having
an outer casing
and an inner tube, the outer casing including intake slots positioned above a
pump intake at a
bottom end of the inner tube, the intake slots allowing the fluid mixture to
enter the space
between the outer casing and inner tube; causing the fluid mixture to flow
downward toward
the pump intake, wherein the fluid mixture reaches a downward velocity
sufficient to allow
the particulate matter in the fluid mixture to continue downward as the fluid
is drawn into the
inner tube through the pump intake; and passing the fluid mixture through a
filter stage
wherein the fluid mixture is drawn through a filter medium to filter the
particulate matter
from the fluid mixture.
[0004c] Certain exemplary embodiments can provide a sand separator
for
removing particulate matter from a fluid in a petroleum production well, the
sand separator
comprising: an inner tube; an outer casing enclosing the inner tube intake
slots along an
upper end of the outer casing to allow the fluid mixture to enter the space
between the outer
casing and inner tube and to flow downward; a pump intake at a lower end of
the inner tube,
wherein the intake slots are positioned above the pump intake, and wherein the
diameter of
the pump intake is selected such that the fluid mixture reaches a downward
velocity sufficient
to allow the particulate matter in the fluid mixture to continue downward into
a mud anchor
below the velocity stage as the fluid is drawn into the inner tube through the
intake.
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[0005] In another embodiment of a particulate separator for use with
a
petroleum production well producing a fluid mixture including particulate
matter is
described. The separator includes a velocity stage having an outer casing and
an inner tube,
the outer casing including intake slots allowing the fluid mixture to enter
the space between
the outer casing and inner tube and to flow downward toward a pump intake at a
bottom end
of the inner tube, wherein the fluid mixture reaches a downward velocity
sufficient to allow
the particulate matter in the fluid mixture to continue downward as the fluid
is drawn into the
inner tube through the pump intake, and a filter stage wherein the fluid
mixture is drawn
through a filter medium to filter the particulate matter from the fluid
mixture.
[0006] In another embodiment a method for separating particulate
matter from
a fluid mixture for use with a petroleum production well producing is
described. The method
includes drawing the fluid mixture into a velocity stage having an outer
casing and an inner
tube, the outer casing including intake slots allowing the fluid mixture to
enter the space
between the outer casing and inner tube. The method further includes causing
the fluid
mixture to flow downward toward a pump intake at the bottom end of the inner
tube, wherein
the fluid mixture reaches a downward velocity sufficient to allow the
particulate matter in the
fluid mixture to continue downward as the fluid is drawn into the inner tube
through the
pump intake, and passing the fluid mixture through a filter stage wherein the
fluid mixture is
drawn through a filter medium to filter the particulate matter from the fluid
mixture.
[0007] The foregoing has outlined rather broadly the features and
technical
advantages of the present invention in order that the detailed description of
the invention that
follows may be better understood. Additional features and advantages of the
invention will
be described hereinafter which form the subject of the claims of the
invention. It should be
appreciated by those skilled in the art that the conception and specific
embodiment disclosed
may be readily utilized as a basis for modifying or designing other structures
for carrying out
the same purposes of the present invention. It should also be realized by
those skilled in the
art that such equivalent constructions do not depart from the spirit and scope
of the invention
as set forth in the appended claims. The novel features which are believed to
be
characteristic of the invention, both as to its organization and method of
operation, together
with further objects and advantages will be better understood from the
following description
when considered in connection with the accompanying figures. It is to be
expressly
understood, however, that each of the figures is provided for the purpose of
illustration and
description only and is not intended as a definition of the limits of the
present invention.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0008] For a more complete understanding of the present invention,
reference
is now made to the following descriptions taken in conjunction with the
accompanying
drawings, in which:
[0009] FIG. 1 is a diagram of a petroleum producing well showing an
existing
sucker rod pump assembly to provide artificial lift;
[00010] FIG. 2 is a diagram of a petroleum producing well showing
utilizing a
progressive cavity pump to provide artificial lift the well including an
embodiment of a sand
separator according to the concepts described herein;
[00011] FIG. 3 is a diagram of the embodiment of a sand separator
shown in
Figure 2 according to the concepts described herein; and
[00012] FIG 4 is a diagram of an alternate embodiment of a velocity
stage
incorporating a vortex producing mechanism.
DETAILED DESCRIPTION OF THE INVENTION
[00013] Referring now to Figure 1, a diagram of a typical sucker rod
pump
used in oil wells is described. The sucker rod pump is described only for the
purposes of
illustrating the operation of a typical oil well and is not intended to be
limiting in any manner
as the present invention is applicable to any producing oil well including
those using any
means of artificial lift, such as rod pumping, electric submersible pumps,
progressive cavity,
and other methods.
[00014] Well 10 includes well bore 11 and pump assembly 12. Pump
assembly
12 is formed by a motor 13 that supplies power to a gear box 14. Gear box 14
is operable to
reduce the angular velocity produced by motor 13 and to increase the torque
relative to the
input of motor 13. The input of motor 13 is used to turn crank 15 and lift
counter weight 16.
As crank 15 is connected to walking beam 17 via pitman arm 18, walking beam 17
pivots and
submerges plunger 19 in well bore 11 using bridle 20 connected to walking beam
18 by horse
head 21. Walking beam 17 is supported by sampson post 22.
[00015] Well bore 11 includes casing 23 and tubing 24 extending
inside casing
23. Sucker rod 25 extends through the interior of tubing 24 to plunger 19. At
the bottom 25
of well bore 11 in oil bearing region 26, casing 23 includes perforations 27
that allow
hydrocarbons and other material to enter annulus 28 between casing 23 and
tubing 24. Gas is
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permitted to separate from the liquid products and travel up the annulus where
it is captured.
Liquid well products collect around pump barrel 29, which contains standing
valve 30.
Plunger 19 includes traveling valve 31. During the down stroke of the plunger,
traveling
valve is opened and product in the pump barrel is forced into the interior of
tubing 24. When
the pump begins its upstroke, traveling valve 31 is closed and the material in
the tubing is
formed forced up the tubing by the motion of plunger 19. Also during the
upstroke, standing
valve 30 is opened and material flows from the annulus in the oil bearing
region and into the
pump barrel.
[00016] As can be seen from Figure 1, where the product
flowing into the well
bore contains sand and other particles, those particles can enter the pump and
plug or cause
damage to the pump mechanism, as well as the casing and tubing and above
ground lines and
tanks. Where there is sand and other particles mixed into the product, as can
occur naturally
or through fracking, it would be helpful to have a mechanism for separating
the sand and
particulates from the hydrocarbon product.
[00017] The present invention provides mechanisms for
separating particulate
matter from the well product. In preferred embodiments the mechanisms of the
present
invention consists of one or two individual stages for accomplishing the
separation, which
can work in tandem or be run as single assemblies.
[00018] Referring now to Figure 2, an embodiment of a down-
hole sand
separator according to the concepts described herein is shown used in a
production well
incorporating a progressive cavity pump. Well 40 is formed by casing 44 and
tubing 45 and
includes pump section 41 and two stage sand separator 42. Pump section 41
includes motor
43 which drives shaft 51. Shaft 51 turns rotor and stator 46, which provides
the lift for the
well product entering well 40. Torque anchor 47 prevents motor 43 from turning
tubing 45
within casing 44.
[00019] Sand separator stage 42 is preferably formed as a two
stage separator
having stage one 49 and stage two 48 which will be discussed in greater detail
with reference
to Figure 3. Mud anchor 50 serves as a catch area for any foreign matter or
solids removed
from the production fluid. While a two stage sand separator is shown as a
preferred
embodiment, either stage could be used in alone or together in any combination
within the
well and still be within the scope of the concepts described herein.
[00020] Referring now to Figure 3, a preferred embodiment of
the sand
separator 40 is described. Stage one 49 is known as the velocity stage.
Production fluids
enter velocity stage 49 through intake slots 57 in the outer casing 58 and
proceed along flow
CA 02784184 2015-11-25
path 51 down toward pump intake 53. Downward velocity of the production fluids
increases
as the mixture moves toward pump intake 53. Under chosen velocities, momentum
of the
heavier solid particulates in the fluid mixture are unable to reverse
direction at pump intake
53 and continue into mud anchor 50, shown in Figure 2, through outlet 54. By
choosing the
relative diameters of the outer casing 58 and inner tube 52 the downward
velocity of flow
path 51 and the upward, or suction velocity of flow path 55 can be controlled
allowing the
optimum velocity for the fluid mixture to be selected to reduce any vacuum
effect at pump
intake 53. Larger diameters for the inner tube 52 can designed to have a large
relative
diameter to reduce the intake velocity. A key to successful separation is to
insure that the
downward velocity of the gas, liquids, and particulates is greater than the
upward intake
velocity.
[00021] Through testing it has been determined that most particulates
fall
through liquid at a rate of .5 to 1.5 feet per second depending upon their
mass and the
viscosity of the liquid that the particulates are moving through. Once the
liquid and gas now
free of particulates have entered pump intake 53, the mixture is able to move
into the inner
tube and travel up to the surface of the well.
[00022] Stage two 48 is the filter stage. Filter stage 48 is a tubular
casing that
is preferably filled with some type of filtering material 56 that the produced
gas, liquids, and
particulates must pass through. As the matter flows along flow path 55 through
the filter,
particulates are captured in the filter media 56 and not allowed to continue
to flow to the
surface or to enter and damage other down-hole equipment. The filter media is
held in the
casing by retention screens at the input end and the output end of the casing
The filter media
can be any known filter media including such media as gravel, rock, sand,
wood, plastic or
other permeable substance suitable for the application.
[00023] As described above, either of the individual stages of the
sand
separator can be used independently of the other stage as a standalone sand
separation device
where the combined device is not practical or appropriate. For example, the
filter stage 48
can be used as a standalone sand filter in horizontal wells where the velocity
stage is not
appropriate. Also, the dimensions of each stage, including the length, can be
chosen for the
particular application. While the sand separator of the present invention has
been shown in
conjunction with mechanisms to provide artificial lift, such as a sucker rod
pump, a
progressive cavity pump or submersible pump, the sand separator of the present
invention can
be used with a naturally flow well or a well with any other type of artificial
lift mechanism.
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[00024] Referring now to Figure 4, an alternate embodiment of the
velocity
stage of the separator according to the concepts described herein is shown. A
continuous fin
or a series of fins 60 are placed in the spacing between the outer casing and
the inner tube.
The fin 60 is preferably place in the lower section of the velocity stage and
direct the fluid
mixture radially downward. The radial flow of the fluid creates a vortex that
is used to
further aid in the removal of particular matter from the fluid mixture as the
fluid in drawn up
in to the pump input.
[00025] Although the present invention and its advantages have been
described
in detail, it should be understood that various changes, substitutions and
alterations can be
made herein without departing from the scope of the invention as defined by
the appended
claims. Moreover, the scope of the present application is not intended to be
limited to the
particular embodiments of the process, machine, manufacture, composition of
matter, means,
methods and steps described in the specification. As one of ordinary skill in
the art will
readily appreciate from the disclosure of the present invention, processes,
machines,
manufacture, compositions of matter, means, methods, or steps, presently
existing or later to
be developed that perform substantially the same function or achieve
substantially the same
result as the corresponding embodiments described herein may be utilized
according to the
present invention. Accordingly, the appended claims are intended to include
within their
scope such processes, machines, manufacture, compositions of matter, means,
methods, or
steps.
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